Wave guide rotary switch



Sept. 5, 1961 D. OLlVlERl ETAL WAVE GUIDE ROTARY SWITCH Filed April 5,1958 INVENTORS DANIEL OLIVIERI LEE W. F0 ER BY :2 g

' ATTORNEY r 2,999,213 WAVE GUIDE ROTARY SWITCH Daniel Olivieri,Yonkers, and Lee W. Forker, B'ayville, N.Y., assignors to Sperry RandCorporation, Great Neck, N.Y., a corporation of Delaware Filed Apr. 3,1958, Ser. No. 726,219 6 Claims. (Cl. 333-7) This invention relates torotary switches for use in wave guide transmission lines.

In microwave communication systems it is often required that it bepossible to selectively connect one wave guide transmission line to anyone of a plurality of other wave guide transmission lines. This is mostoften accomplished in rectangular wave guide transmission lines byemploying a rotary switch wherein the different wave guide transmissionlines are disposed about, and are in communication with, a hollow cavityin a stator member of the switch. A cylindrical rotor member having acurved wave guide channel therein is disposed within the stator cavityand is rotatable with respect to said stator member so that the rotorwave guide channel may be selectively positioned to connect one of thestator Wave guide transmission lines to any one of several other statorwave guide transmission lines.

The rotor wave guide channel may be curved in a plane parallel to theelectric field vectors of the waves propagating in the wave guides, an Eplane bend, or may be curved in a plane parallel to the magnetic fieldvectors of the waves, an H plane bend. Because of the propagatingcharacteristics of a transverse electric wave in a rectangular waveguide it is possible to make a sharper bend in the E plane than in the Hplane. Therefore, where the size and weight of the rotary switch areimportant factors, it is desirable to employ an E plane bend in therotor wave guide channel. E plane rotary switches, however, quite oftensuffer from poor isolation between selected and non-selected wave guidechannels and high VSWR in the selected channels. This results from thefact that the electric vector of the waves propagating in the waveguides are perpendicular to the axis of the stator cavity, andcylindrical rotor member, and may propagate in the gap which separatesthe stator and rotor members.

One means that has been used in the past to improve the isolationbetween selected and non-selected wave guide channels and to reduce theVSWR in the selected channels is to employ quarter wavelength chokes inthe well known manner in the rotor or stator members. This method hasbeen successful in some instances but the switch is inherently a narrowband device since the quarter wavelength chokes are frequency sensitive.Additionally, if the quarter wavelength chokes are placed in the rotormember the rotor must be large enough to accommodate the slots whichcomprise the chokes, and the rotor member approaches the size of an Hplane rotor and the advantage of an E plane switch is lost. Dielectricmaterials have been inserted into the choke slots in order to reducetheir lengths, but this has not proved entirely satisfactory since thechokes are still frequency sensitive.

Another difl'iculty which has been encountered in the prior rotary waveguide switches is that at high power levels arcing occurs between therotor and stator members since they are separated by only a small airgap.

It is therefore an object of this invention to provide an E plane rotarywave guide switch which is operable over a wide range of frequencies.

It is another object of this invention to provide a rotary wave guideswitch having a high degree of isolation between selected andnon-selected wave guide channels.

P ice Another object of this invention is to provide a rotary wave guideswitch which produces a low VSWR in the selected wave guide channels.

A further object of this invention is to provide a rotary wave guideswitch which is operable at high power levels.

A still further object of this invention is to provide a small,lightweight rotary wave guide switch.

These and other objects of the invention which will become more apparentas the description proceeds are achieved by providing a stator memberhaving a cylindrical cavity portion and a plurality of wave guidechannels radially extending from the cavity at spaced intervals on itsperiphery. A cylindrical rotor member having at least one wave guidechannel extending therethrough is rotatably disposed within the cavityso that said rotor wave guide channel connects different stator waveguide channels when rotated to different predetermined angularpositions. Said rotor wave guide channel is curved in the E plane. \Aplurality of circumferentially spaced longitudinal slots are disposedabout the cavity wall of said stator and each is positioned immediatelyadjacent a broad wall of a stator wave guide channel. Slideablypositioned within each slot is a solid conductive member which has alongitudinal height greater than the broad dimension of said wave guidechannels. Means are positioned within each slot for urging the solidconductive members into a sliding surface contact with the rotor member,and for urging said conductive member into a surface contact with onewall of its respective slot.

The invention will be described in connection with the followingdrawings, wherein:

FIG. 1 is a plan view of the novel rotary switch of this invention;

FIG. 2 is a sectional view of the rotary switch of this invention takenat section 22 of FIG. 1; and

FIG. 3 is a partial sectional view of an alternative rotatable withrespect thereto by means of bearing members 18 and 19, FIG. 2, shown asball bearings.

Rotor member 17 has two curved wave guide channels 40 and 41 extendingtherethrough for providing conductive wave guide paths between differentpairs of stator Wave guide channels when rotated to differentpredetermined angular positions.

Cover members 20 and 21, FIG. 2, enclose the ends of stator member 11and also provide supporting means for the outer races of ball bearingmembers 18 and 19, respectively. The top cover member 20 is providedwith a center aperture 22 through which passes the shaft 23. Shaft 23may be coupled to actuating means, not shown, for rotating rotor member17. Screws such as 24, 25 and 26, 27 secure cover members 20 and 21,respectively, to stator member 11. An O-ring 28 of suitable material ispositioned in a groove 29 in bottom cover member 21 for providing anair-tight seal between bottom cover member 21 and stator member 11 sothat the wave guideswitch may be employed in a pressurized Wave guidesystem. Suitable means associated with the rotor actuating means, notshown, provides a pressure seal on top cover member 20.

A plurality of longitudinal slots 30 are circumferentially spaced aroundthe wall of cavity 12 and extend radially into stator member 11. Each ofthe slots is positioned immediately adjacent a broad wall of one of thestator wave guide channels, as will be more fully explained herebelow.

Slideably positioned within each of the slots 30 is a solid conductivemember 31. Each conductive member 31 has a wedge-shaped end which ishoused within the corresponding slot. A wedge-shaped member 32 in eachslot has a surface area in contact with a corresponding surface of eachconductive member 31, A resilient spring member 33 is positioned betweenthe end wall of each slot and the wedge-shaped member 32 and urges thewedge-shaped members 32 outward-1y, and consequently urges conductivemember 31 into sliding contacts with rotor member 17.

Conductive members 31 have longitudinal heights which are greater thanthe width of the broad walls of the wave guide channels, and asillustrated in FIG. 2, preferably have heights at least as great as thelongitudinal dimension of rotor member 17. Conductive members 31 shouldhave heights greater than the width of the broad walls of the wave guidechannels so that the ends of the wave guide channels in rotor member 17may freely pass over the conductive members 31 when said rotor member isrotated. The conductive members 31 provide short-circuiting surfacecontacts with rotor 17 along the entire length of the rotor, and thussubstantially completely block the air gap extending between the rotorand stator members. The ends of conductive members 31 which are insliding contact with rotor 17 are accurately fashioned so as to conformto the cylindrical surface of the rotor 17 and thus assure a goodsurface contact therewith.

Conductive members 31 are preferably made of graphite, or a similarsubstance, or mixture, which possesses the property of having lowelectrical resistivity, and also possesses the property being a drylubricant. Conductive members having these properties will provide agood electrical short circuit between the stator and rotor members, andwill also provide a low friction, sliding contact with rotor 17.

In practice, conductive members made of graphite, and also made ofGraphalloy, grade 411, :a graphite and silver particle mixture which isa product of Graphite Metallizing Corporation, have been used with greatsuccess.

The operation of a wedge-shaped member 32 on a conductive member 31' maybe explained as follows. The angle of the taper of the wedges on members31 and 32 are diiferent for reasons which will now become apparent.Spring 33 urges wedge-shaped member 32 outwardly, and in turnwedge-shaped member 32 exerts a force against conductive member 31.Because the two surfaces are inclined at diiferent angles to thedirection of the exerted force, it may be considered that two componentforces are acting on the conductive member 31, one component beingdirected radially along the slot and urging conductive member 31outwardly, and the other component, resulting from the wedging action,being directed transversely to the slot and urging the conductive memberlaterally against the side wall of the slot. In this manner eachconductive member 31 is caused to make a good surface contact with rotormember 17 at its outer end, and is also caused to make a good surfacecontact over one of its sides with the wall of the slot 30 in statormember 11.

Slots 30 are positioned as close to a broad Wall of a wave guide aspossible so that the electrical short presented by conductive members 31are reflected back along the air gap to the cavity ends of the statorand rotor wave guides without any substantial impedance inversion, thuscausing no appreciable discontinuity to appear in the wave guide pathjoining the stator and rotor wave guide channels. Because the distancebetween the cavity ends of the stator and rotor wave guide channels andthe nearest conductive members 31 is a very small fraction of a waveguide wavelength of the waves propagating in the wave guide channels,the frequency of the waves may vary over a considerable frequency rangewithout any appreciable change in the efiective short circuit presentedat the junction of the stator and rotor wave guide broad walls. In awave guide switch constructed in accordance with the principles of thisinvention, the electrical distance between each conductive members 31and the nearest wave guide channel was less than wave guide wavelengthat the center of the operating frequency band.

FIG. 3 is a partial plan view illustrating an embodiment of the presentinvention wherein the slots 30 are positioned in the rotor member 17.Solid conductive members 31, wedge-shaped members 32, and spring members33 are disposed within slots 30 in the manner explained above.

One possible disadvantage of placing the slots on the rotor member isthat the size of the rotor may have to be increased in order toaccommodate the slots.

It will be noted in FIG. 1 that conductive members 31 and wedge-shapedmembers 32 are positioned so that conductive members 31 are urged into asurface contact with the side of the respective slots which is locatednearest an adjacent stator wave guide broad wall. This assures that theshort circuit produced by a conductive member 31 appears as close aspossible to the adjacent stator and rotor wave guide broad walls.Because conductive members 31 possess the property of having lowelectrical resistivity and are in a surface contact with both the rotor17 and stator 11, the short circuit is of excellent quality, and bymaking the conductive members of graphite or a similar dry lubricantmaterial, a relatively small actuating force is required to rotate rotormember 17.

An embodiment of the present invention constructed substantially asillustrated in FIGS. 1 and 2 had the following approximate dimensions:

Slots 30- 1.78 X .172" Conductive Members 31- 1.765" x .167"Wedge-Shaped Member 32 .156

35:|;030' .125 (less than Mo wave guide wavelength at center offrequency band) Wedge on end of Conductive Member 31 Wedge onWedge-Shaped Member 32 Distance Between Slot and Nearest Wave GuideBroad Wall.

In the operation of the novel switch of this invention over thefrequency range of 7,000 me. to 10,000 mc., the VSWR in selected waveguide channels varied from a minimum of 1.03 to a maximum of 1.09, andthe minimum isolation of the non-selected wave guide channels was 70 db.The power handling capability of the switch was at least as great as thecapabilities of the system in which it was operated.

While the invention has been described in its preferred embodiments, itis to be understood that the words which have been used are words ofdescription rather than of limitation and that changes within thepurview of the appended claims may be made without departing from thetrue scope and spirit of the invention in its broader aspects.

What is claimed is:

1. A wave guide rotary switch comprising, a stator member having acylindrical cavity portion and a plurality of rectangular wave guidechannels radially extending from said cavity at spaced intervals on theperiphery thereof, a cylindrical rotor member having at least onerectangular wave guide channel extending therethrough and beingrotatably disposed within said cavity, said stator and rotor wave guidechannels having their broad walls disposed parallel to the longitudinalaxis of said cavity, first and second end plate members for enclosingthe ends of said cavity and providing means for supporting said rotormember, a plurality of longitudinal slots radially disposed about theinner surface of said stator member, said slots having lengths greaterthan the wide dimension of said wave guide channels, each of saidlongitudinal slots being separated from a broad wall of a wave guidechannel by a distance which is considerably less than one-quarter waveguide wavelength of waves propagating through said channels, elongatedconductive members having lengths greater than the wide dimensions ofsaid wave guide channels positioned in each of said slots and eachhaving a longitudinal surface slideably contacting said rotor member,said conductive members having a wedge-shaped end disposed within saidslots, a wedge-shaped member within each of said slots and makingcontact over a portion of its wedged surface with the similarly shapedend of said conductive member, and means for urging said wedge-shapedmembers against said conductive members, whereby said conductive membersare urged against a wall of said slot nearest the adjacent wave guidechannel.

2. A wave guide rotary switch comprising, a stator member having acylindrical cavity portion and a plurality of rectangular wave guidechannels radially extending from said cavity at spaced intervals on theperiphery thereof, a cylindrical rotor member rotatably disposed withinsaid cavity and having at least one rectangular wave guide channelextending therethrough for providing a conductive wave guide pathbetween diiferent pairs of stator wave guide channels when rotated todifierent predetermined angular positions, said stator and rotor waveguide channels having their broad walls disposed parallel to thelongitudinal axis of said cavity, a plurality of circumferentiallyspaced longitudinal slots extending radially into the cylindrical wallat said stator, each of said slots being positioned immediately adjacenta broad wall of a wave guide channel, a solid conductive member having alongitudinal height at least as great as the height of said rotor memberslideably disposed in each of said slots, the outwardly extendinglongitudinal surface of each conductive member being conformal to thecylindrical surface of said rotor member, and a spring biasedwedge-shaped member disposed in each of said slots to urge therespective conductive member outwardly and into a slideable contact withsaid rotor member and to urge the conductive member transversely andinto a surface contact with the side of said slot.

3. A wave guide rotary switch comprising a stator member having acylindrical cavity portion and a plurality of wave guide channelsextending outwardly from said cavity at spaced intervals on theperiphery thereof, a cylindrical rotor member rotatably disposed withinsaid cavity and having at least one wave guide channel extend ingtherethrough, said rotor channel being located to bring the ends thereofinto registration with the ends of different pairs of stator wave guidechannels when the rotor is rotated to different predetermined angularpositions, a plurality of elongated conductive members extending betweensaid stator and rotor members at spaced intervals around the peripheryof said cavity, said conductive members having longitudinal dimensionsparallel to the center axis of said cavity greater than the maximumcross-sectional dimensions of said wave guide channels, each of saidconductive members having longitudinally extending surface areasextending substantially through out its entire length in contact withsaid rotor and stator members to provide a short circuit connectionbetween the rotor and stator members, at least one of said contactingsurface areas of each of said conductive members making a slidingcontact during rotation of said rotor member, and each of saidconductive members being positioned from the end of a stator wave guidechannel by a distance considerably less than one quarter wave guidewavelength when said rotor wave guide channel is in registration with apair of stator channels.

4. A wave guide rotary switch comprising a stator member having alongitudinal cavity portion and a plurality of wave guide channelsextending outwardly from said cavity at spaced intervals on theperiphery thereof, a cylindrical rotor member rotatably disposed withinsaid cavity and having at least one wave guide channel extendingtherethrough for providing a conductive wave guide path betweendifferent pairs of stator wave guide channels when rotated to differentpredetermined angular positions, a plurality of circumferentially spacedlongitudinal slots extending into the cavity wall of said stator, eachof said slots being separated from the cavity end of a stator wave guidechannel by a distance substantially less than one quarter wave guidewavelength, a solid conductive member having a longitudinal heightgreater than the longitudinal dimension of a wave guide channel slidablydisposed in each of said slots, and means for urging each of saidconductive members outwardly into contact with said rotor member andtransversely into contact with a wall of its respective slot, thecontacts between said conductive members and said rotor member beingsliding contacts during rotation of said rotor member.

5. A wave guide rotary switch comprising a stator member having acylindrical cavity portion and a plurality of wave guide channelsextending outwardly from said cavity at spaced intervals on theperiphery thereof, a cylindrical rotor member rotatably disposed withinsaid cavity and having at least one wave guide channel extendingtherethrough, said rotor channel being rotatable to bring the endsthereof into registration with the ends of different pairs of statorwave guide channels, a plurality of elongated conductive elementsextending between said stator and rotor members at spaced intervalsaround the periphery of said cavity, said conductive elements havingaxial dimensions parallel to the center axis of said cavity greater thanthe maximum cross-sectional dimensions of said wave guide channels, eachof said conductive elements being slidably positioned in a longitudinalslot in one of said members, each of said conductive elements havinglongitudinally extending surface areas extending substantiallythroughout its entire length in contact with said rotor and statormembers to provide a short circuit connection therebetween, and meansdisposed in each of said slots for urging said conductive elementsoutwardly into contact with the other of said members to maintain saidcontact during rotation of said rotor member, each of said slots beingpositioned immediately adjacent a rotor wave guide broad wall when saidrotor is in one of its registering positions.

6. The combination of claim 5 wherein said conductive members arecomprised of a material which possesses the property of beingself-lubricating.

References Cited in the file of this patent UNITED STATES PATENTS2,556,869 Charles June 12, 1951 2,573,713 Kannenberg Nov. 6, 19512,683,255 Koos July 6, 1954 2,705,776 Starr Apr. 5, 1955 2,763,844Kruger Sept. 18, 1956

